Regenerator seal



United States Patent 11113,54z,12z

[72] Inventor Joseph W. Bracken, Jr. [56] I References Cited ksdfordTownship, Michigan UNITED STATES PATENTS P 7699 3,192,998 7/1965 Chute165/9 [22] F'led s 234 999 2/1966 Atwo 1 165/9 [45] paemed 3'2739039/1966 Cha :iaii i i l65/9X [73] Assignee General Motors Corporation p eDetroit, Michigan Primary Examiner-Albert W. Davis, Jr. a corporation fD l w Attorneys Paul Fitzpatrick and E. W. Christen ABSTRACT: Anaxial-flow rotary regenerator has fluid seals which extend between thefixed housing of the regenerator and the matrix and conform to theperimeters of the fluid flow paths. The seals can yield to distortionsof the matrix or housing. Each seal includes a matrix-engaging element,a flexible [54] REGfNERQTOI: S 5?- sealing membrane engaging the housingand welded to the 5 ch 4 matrix-engaging element, a supporting membranedisposed on [52] U.S. Cl. 165/9, the low pressure side of the sealingmembrane, and a support 277/96 plate disposed on the low pressure sideof the supporting [51] int. Cl. F28d 19/04 membrane. The support platehas a hinged connection to the [50] Field of Search l65/9; matrixengaging element through an abutment strip welded to I 277/96 thematrix-engaging element.

46 4'0 ,59 56, 45 /0 1m /7 W 7 I y V W v i m 57 PRESSURE GHER PRESSURE5:;

1/1/1111nun/m1 1/111mmmm11111111111111 Patented Nov. 24, 1970 3,542,122

LOWER PRESSURE INVENIOR 1/ Brackemf:

BY 1424 M TTORN EY ,nscENsnAro issA My invention relatesto improvementsin sealing arrangements for rotary regenerators, particularly those ofthe axial! flow type. Such-regenerators are devices in which a finelyporous metal or ceramic disk isslowly rotated so that each element ofthe disk passes successively through two gas paths, absorbing heatfrom'the hotter gas and releasing it to the cooler gas. 1

One application of such-regenerators" is in preheating the combustionair in gas turbineengin'es. In this case, there is a large pressuredifferent between the compressed air which is heated and the turbineexhaust gases which giveup heat. In order to prevent leakage of the highpressure fluid into the low pressure fluid path and also to prevent eachfluid from bypassing thematrix, seals are provided which extend aroundthe perimeter of one orboth'flow paths on each face of the regenerator,bridging the gap between the regenerator disk and a face of theenclosing housing which is proximate to the matrix. Particularly withmetal'matrices, sealing problems are aggravated by distortion of thematrix due to the large temperature gradient between the two faces.

Because of the relative warping of the matrix and the housing andbecause of the .very high temperatures of the regenerator when employedwith gas turbines, the provision of an adequate, durable, andeconomically practicable seal has presented difficult problems. Thepurpose of my invention is to provide a seal between a rotaryregenerator matrix and the matrix housing which is exceptionallyeffective, is durable and reliable, and which can be fabricated at areasonable cost.

The principal objects of my invention are to advance the art of rotaryregenerators, tomake such regenerators commercially feasible forapplications such as gas turbine engines, and to provide an improvedseal for a rotary regenerator. A further object is to-provide a simplesealhaving'a minimum of leakage paths, p I

The nature of my invention and its advantages will be clear to thoseskilled in the art from the succeeding detailed description of thepreferred embodiment of the invention and the accompanying drawingsthereof.

FIG. 1 is a schematic view of'a rotary regenerator taken in a planecontaining the axis of rotation of the matrix.

FIG. 2 is asectional view of a regenerator embodying my improved sealtaken ona plane perpendicular to the axis of rotation as indicated bythe line 2-2 in FIG. 1.

FIG. 3 is an enlarged view of a portion of the seal as illustrated inFIG. 2. l

, FIG. 4 is a still further enlarged cross-sectional view taken on theplane indicated by the line 4-4 in FIG. 3.

Before proceeding to the detailed description, it may be mentioned thatthe invention is described as embodied in an axial flow regenerator er,the type to which Chapman et al. US. Pat. No. 3,273,903for RegeneratorSeal for a Gas Turbine Engine, Sept. 20, I966, Bracken et al. US. Pat.No. 3,368,611 for Rotary Regenerator Seal with High Pressure FluidRecovery, Feb l3, 1968, and Bracken et al. U.S. Pat. No. 3,476,173 aredirected. V l

Referring first to FIG. 1 the regenerator comprises a housing which isgenerally drum shaped and which enclosesfan annular matrix 11 which isof a structure defining pores or passages l2'( greatly'enlarged inFIG. 1) extending from face to face of the matrix generally parallel toth e'axis of rotation defined by a matrix locating and driving shaft 13.Shaft 13 is mounted in suitable bearings in a boss 15 on the housing andterminates in a spider 17 which is coupled to the matrix by means (notillustrated, which may be of the type described in U.S. Pat. No.3,476,173,);so'that the matrix may be rotated slowly. The matrixpreferably includesa nonporous inner rim 18 and an outer nonporous rim19. It is not essential that such rims be provided, however. A generallycylindrical space 21 is defined withinthe interior of the matrix and aspace 22 extends around the peripheryof'the'matrix within the housing10. An inlet 23 for'cool high pressure air enters one face of thehousing and opposite to it an outlet 25 is provided for the heatedcompressed 'air. The hot low pressure exhaust gases enter through aninlet 26 and leave the regenerator through an outlet 27, the two streamsbeing thus in counterflow relation, although this is not essential tothe invention. Also, the hot gas passage is of larger area than the coldair passage because of the difference in density, but this also ismerely incidental to the invention. I

A sealing means or seal assembly 28 is provided between each face of thematrix and the housing to confine the cold and hot gases to the desiredpaths through the matrix from inlet to outlet and minimize leakagebetween the paths. As

outerrim of the matrix by an arcuate rim or bypass seal 34 extendingaround the highpressure path and an arcuate rim seal 35 extending aroundthe low pressure path. The seal assembly thus defines an opening 37 forthe heated high pressure air and an opening 38 for the hot low pressureexhaust gases, these openings as shown in FIG. 2 conforming generally tothe outline of the ducts 25 and 26.

The seal arms 30 and 31 together may be termed a cross arm seal, thislying between the high pressure and low pressure fluid paths and theseal portions 34 and 35 may be termed a rim seal or bypass seal, thesebeing engaged with the matrix adjacent its periphery. The rim sealportion 34 and the cross arm seal surround the high pressure passage andthe cross arm seal and rim seal portion 35 surround the low pressure gaspassage. It is common practice for the high pressure air to occupy thespace 22 radially outward of the matrix, in which case the rim sealportion 34 may be omitted at the entrance 23 to the matrix.

Proceeding now to FIGS. 2, 3, and 4 for a detailed description ofpreferred structure of the sealing means, these FIGS. are views of theseal at the outlet side of the air path and the inlet side of the gaspath. The principal structural element of the seal is a carrier orframe40 which, in this particular seal, consists of a circular portionforming part of the rim seals 34 and 35 and an angular cross arm portionextending'through the cross arm seal portions 30 and 31. Preferably,this is a unitary structure of rather heavy sheet metal so that it isrigid in the direction perpendicular to the axis of rotation of thematrix but is capable of flexing to a certain extent in a directionparallel to the axis of the matrix. In the particular example describedherein which the seal is approximately two feet in overall diameter, thecarrier 40 is about 0.06 inch thick. This frame 40 is located positivelyagainst rotation and translatory movement transverse to the axis ofrotation, but is free to move parallel to the axis of rotation of thematrix. This mounting is provided by a number of pins or dowels 41 pro-.jecting from the fixed structure of the housing 10 into slots 42 in lugs43 extending radially outward from the frame 40. The slots 42 areelongated to provide for relative radial expansion of the carrier 40 andthe regenerator housing 10. The carrier 40 bears a wear element 45 whichis in actual contact with the matrix throughout the circumference of therim seals and along the length of the cross arm seals. The wear elementis corhposedof a material or materials suited to the require ments ofthe installation..lt may be, for example, a graphite composition or anickel alloy. The wear element may be attached in any desired manner tothe face of the carrier as by brazing, riveting, or other fasteningmeans. The wear element also may be about 0.06 inch thick in thedescribed embodiment. The carrier and the wear element together may becalled a matrix-engaging strip or element 44.

The structure so far described may be considered to be embodied in theprior art.

The structure to which my invention is directed lies in the means forbridging the gap 46 between the carrier 40 and a plane face 48 of thehousing 10 which underlies the strip 44. Because of the dishing or otherdistortion and expansion of the matrix as it heats up and possibledistortions and expansion of the case, the width of gap 46 varies notonly with operating conditions of the regenerator but also varies fromone area to another along the strip 44. The problem is, therefore, toprovide a high temperature resistant seal which adapts itself tovariation in the width of the gap 46 and substantially entirely preventsleakage from the higher pressure to the lower pressure through the gap46.

The structure provided for this purpose, shown most clearly in FIGS. 3and 4, embodies four elements comprising a seal disposed between thecarrier or frame 40 and the housing surface 48 and bridging the gap 46.These parts of the seal, in order from the carrier 40, are a sealingmembrane 49, a supporting membrane 50, a support plate 52, and a hingeelement or abutment strip 53. Parts 53, 50, and 49 are all weldedtogether and to the carrier 40 by a row of spot welds or a seam weld or,if desired, attached by mutual brazing along the portion or line 54where all of these parts are stacked together adjacent one edge ofcarrier 40. This weld or other joint is such as to provide a leaktightconnection between the sealing membrane 49 and the frame. The free edgeof the sealing membrane 49 bears against the face 48 of the housingunder the influence of the differential of gas pressures. As indicatedin FIG. 4, the higher pressure is underneath or to the left of thesealing membrane and the lower pressure above or to the right of themembrane. The membrane 49 is of very thin sheet metal so that it isreadily deflected by the pressure into close substantially leakproofsealing engagement with the surface 48. In the particular example thisis of 0.002 inch shim stock. Since such very light weight and flexiblematerial could not act as a piston to withstand the force exerted by thegas pressure differential, the parts 50 and 52 reinforce it and providethe necessary stiffness except at the free edge where the seal ismaintained In the described example, the support plate 52 is some threeto four hundredths inch thick and approximately one-half inch in width.It,.therefore, provides the necessary stiffness to support the pressureload. However, since such a structure would resist the gradual change inwidth of the gap 46 from one area of the matrix to another, it isnecessary to reduce the torsional stiffness of the support plate. Thisis accomplished by slots 56 extending substantially across the width ofthe support plate so that, apart from a connecting portion 57 at oneedge of the plate, it essentially amounts to a number of side-by-sidebars extending between the carrier and the housing.

One edge of the support plate 52 bears against a flange 58 of the hingeelement 53 so that the support plate is free to swing about itsright-hand edge, as illustrated in FIG. 4, to accommodate variations inwidth of gap 46. The flange 58 is broken by closely spaced slots 60 sothat it does not unduly stiffen the carrier 40 and thus lessen theability of the carrier to accommodate to the curvature of the matrix.

The supporting membrane 50 serves two functions; it bridges the slots 56in the support plate to prevent undue local loading and wear of thesealing membrane 49 while maintaining the flexibility of the supportplate 52. Also, it serves to retain the support plate in positionagainst the hinge element 53. In the particular example, this membraneis 0.004 inch thick. As shown clearly in FIGS. 3 and 4, the outer edgeof the supporting membrane 50 is slotted in line with the slots 56 toprovide tabs 59 which are doubled back over the edge of the supportplate 52 to hold it against the hinge element 53. Note that this outeredge of plate 52 is tapered or feathered to a relatively thin edge sothat the sealing membrane 49 is supported down to a point closelyadjacent to the surface 48. As will be seen, the structure illustratedprovides a seal between the strip 44 and the housing which has but oneleakage path, that being at free edge of the sealing membrane 49, andwhich has structure of great simplicity.

As indicated in FIG. 3, where the cross arm seal joins the rim seal theportions or parts 49,50, 52, and 53 are mitered so as to provide asuitable corner joint. A similar miter is provided at the angle betweenthe cross arm seal portions 30 and 31. The rim seal portion 34 is notillustrated in FIG. 3. However, it is mitered into the junction betweenthe other two seals.

It will be apparent to those skilled in the art that the preferredstructure described provides a sealing structure for a rotaryregenerator having superior simplicity, a minimum of leakage, and, ingeneral, a structure of great practicality and usefulness.

The detailed description of the preferred embodiment of the inventionfor the purpose of explaining the principles thereof is not to beconsidered as limiting or restricting the invention, since manymodifications may be made by the exercise of skill in the art withoutdeparting from the scope of the invention.

Iclaim:

1. In a rotary regenerator including a housing and a heattransfer matrixrotatable in the housing about an axis, the matrix and housing definingspaced faces having a gap between them, the housing face being flat, thegap being variable in operation of the regenerator, sealing meansbridging the said gap adaptable to variation of the gap comprising, incom bination, a matrix-engaging strip, plate means hinged to the stripbridging the gap between the strip and the housing face, the plate meansbeing torsionally yieldable to accommodate convergence of the gap alongthe strip, the plate means being feathered to provide a thin edge at theedge engaging the housing face, and a thin flexible sealing membranesealingly bonded to the strip, supported by the plate means across thegap, and having an edge extending beyond the plate means into flexuralengagement with the flat housing face, the sealing means being sodisposed that the pressure differential across the sealing means biasesit toward the housing face.

2. A structure as defined in claim 1 in which the plate means is formedwith slots to provide the torsional yieldability.

3. A rotary regenerator comprising a housing defining two flow pathsrespectively for fluids at different pressures, means defining a fluidinlet to and a fluid outlet from the housing for each flow path, anaxial-flow heat exchange matrix mounted in the housing was to extendacross both flow paths, the matrix being pervious to fluid flow andbeing adapted to transfer heat between the fluids, means for rotatingthe matrix about an axis so that elements of the matrix are alternatelyheated by one fluid and cooled by the other fluid, and sealing meanssealing between the housing and the matrix to confine each fluid to itsflow path; the sealing means comprising, in combination, amatrix-engaging strip extending along a boundary of a said flow path,the housing having a flat face underlying and spaced from the saidstrip; means extending between the said strip and the housing locatingthe strip with respect to the matrix with freedom for movement axiallyof the matrix to conform to the face of the matrix; a seal bridging thegap between the said strip and the said face of the housing adaptable tovariation of the gap comprising, in combination, plate means hinged tothestrip bridging the gap between the strip and the housing face, theplate means being torsionally yieldable to accommodate convergence ofthe gap along the strip, the plate means being feathered to provide athin edge at the edge engaging the housing face, and a thin flexiblesealing membrane sealingly bonded to the strip, supported by the platemeans across the gap, and having an edge extending beyond the platemeans into flexural engagement with the flat housing face, the sealingmeans being so disposed that the pressure differential across thesealing means biases it toward the housing face.

4. A structure as defined in claim 3 in which the plate means is formedwith slots to provide the torsional yieldability.

5. A rotary regenerator comprising a housing defining two flow pathsrespectively for fluids at different pressures, means defining a fluidinlet to and a fluid outlet from the housing for each flow path, anaxial-flow heat exchange matrix mounted in the housing so as to extendacross both flow paths, the matrix being pervious to fluid flow andbeing adapted to transfer heat between the fluids, means for rotatingthe matrix about an axis so that elements of the matrix are alternatelyheated by one fluid and cooled by the other fluid, and sealing meanssealing between the housing and the matrix to confine each fluid to itsflow path; the sealing means comprising, in

combination, a matrix-engaging: element extending along a boundary of asaid'flow'path, the housing having-a flat face un-.

derlying and spaced from the said element; means extending between thesaid element and the housing'loc'ating the element with respect to thematrix with freedomfor movement axially of the matrix to conform to theface of the matrix; a

seal bridging the gap between the said element and the said supportingmembrane and the said element, the sealing m brane having a-sealing edgeextending beyond the edge of the supporting membrane and support plateinto direct pressurebiased engagement withthe said flat face of thehousing, the

supporting membrane and support plate supporting the sealing memberagainst pressure forces between the sealing edge and the said-element;an abutmentstrip extending along the said element, the saidmembranesextending between the said element and the abutment strip, andthe sealing membrane and element being bonded together in fluid-sealingrelation,

the. edge of th'e support plate adjacent the said element being inhinged engagement with the'abutme'nt strip, the abutment strip being onthe lower pressure side of the support plate so that the higher pressureloads the support plate against the abutment strip.

